Some fanfictions have a plotline where the common room is under a magical curse. Harry and Hermione are the only ones immune to it because of their strong bond. They have to figure out how to break the curse before it spreads throughout Hogwarts. It's a high - stakes plotline that really focuses on their relationship and problem - solving abilities.
In some fanfics, their sibling bond leads to them developing new magical abilities together. For example, they might discover a combined spellcasting technique that no one else can do.
One unique plotline is when Harry and Draco are magically bound to protect each other's families. It forces them to work together and Hermione is the mediator. They have to overcome their past enmity for the sake of their loved ones.
One plotline is that after the rejection, Harry throws himself into his Quidditch or his fight against dark forces even more. Meanwhile, Hermione starts to focus on her own projects and relationships with other characters, like starting a study group with some Ravenclaws. As the story progresses, they might cross paths again and there could be some tension. Sometimes, there could be a plot where Harry starts to develop feelings for another character, like Luna, but still has lingering feelings for Hermione. And the fanfiction might explore how he deals with these mixed emotions.
One interesting plotline could be Hermione and Draco being forced to work together in the Room of Requirement for some school project or task assigned by a teacher. They start off hating each other but gradually come to understand and respect one another as they discover each other's strengths and insecurities within the ever - changing room.
One common plotline is them trying to change the Slytherin house's negative image. They bring their Gryffindor values like bravery and loyalty into Slytherin and try to reform it from within. Another is their relationship with the other Slytherins. They might have to deal with the pure - blood supremacist ideas that some Slytherins hold. Some fanfictions also explore how they adapt to the Slytherin common room and its more secretive atmosphere.
Some fanfictions explore a different relationship dynamic between them. Maybe Harry has a problem that only Hermione can understand and help him with, and this brings them closer in a way that's different from their normal friendship. It could be something related to his connection with Voldemort or his family history.
One common plotline is them working together on a project. For instance, they might be part of a team to reform the Ministry's education policies. Percy brings his administrative knowledge and Hermione her experience as a student and her innovative ideas.
There's often the sacrifice plotline. They might sacrifice their relationship with Hermione to save a large number of people. For instance, they learn that a dark wizard will spare many lives if they abandon Hermione. Also, the jealousy plotline can exist. If a new character becomes closer to Hermione and they feel left out, they might leave out of jealousy and a sense of not belonging in Hermione's new social circle.
One interesting plotline could be Harry and Ginny using the Room of Requirement to hide from Death Eaters during the final battle. They find secret passages and ancient spells within the room that help them in their fight. Another could be them using the room for romantic getaways, away from the prying eyes of Hogwarts students and teachers, where they share their deepest secrets and feelings.
One interesting plotline could be about a character using the Room of Requirement to hide a powerful and dangerous magical artifact that was thought to be lost. The protagonist has to keep it a secret from both the good and bad wizards while trying to figure out what to do with it. Another could be students using the room to create a secret study group for a very advanced and restricted area of magic, and they have to avoid getting caught by the professors. And a third plotline might be about a character who accidentally discovers a hidden passage in the Room of Requirement that leads to an unknown part of Hogwarts filled with ancient magic and mysteries.